To what are you trying to detect current flow?  If it has a removable
power cable (i.e., a computer or monitor), you could make a pigtail
to insert between the wall and the device.  Or you could always put
it between the wall and the power cord.

I like the idea of snugging a core with many windings up agains the
line; that probably wouldn't work unless the individual wires in the
cable are parallel, which usually isn't the case in a three-conductor
cable.

In short, I don't think there is an easy way...but I'm no expert.
I spent a while thinking about this a few years ago, trying to find
a good way to shut down a bank of Mac servers upon failure of
primary power.  Problem was, the backup power was in another
part of the building.  My idea was to sense the current flowing
from the main power to the monitors, put the servers on the
backup power, and detect when the current flow to the
monitor stopped.  At that time, a countdown starts and the
computers are shut down if the current flow doesn't come
back.

Eventually we found a shareware program that would shut
down a Mac if two of the serial port lines were crossed.  We
had to add serail ports, but not too tough.

Mike H.

>What is the smartest and lowest cost method to detect if there is a
>current flowing in a 110/220 V cable, preferably without doing any thing
>else with the wire then to attach something outside of the cable.
>
>/Ake

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